What Is Cladiosporum Mold and Is It Found in Homes?
Last updated October 26, 2026
The short answer
What Does Cladosporium Look Like
Cladosporium colonies often appear as dark green, black, or brown patches with a velvety or powdery texture. It can grow on surfaces such as wallpaper, window frames, and HVAC vents. Because it spreads easily through the air, you might notice it in dusty corners or on fabrics.
Under a microscope, the spores have a distinctive branching structure, but you won't see that with the naked eye. If you suspect cladosporium, a moisture problem is likely present. Look for discoloration on walls, ceilings, or around windows, especially after leaks or condensation.
Where It Grows in Your Home
Cladosporium thrives in damp, poorly ventilated areas. Common spots include bathrooms, basements, and around air conditioning units. It also grows on wet drywall, carpet, and upholstery after water damage, such as from a burst pipe or roof leak.
In damp climates with wet winters and dry summers, indoor humidity can spike during rainy months. Keep an eye on areas that stay moist, like under sinks or behind refrigerators. If you notice a musty smell or visible growth, act quickly to prevent spreading.
- Bathrooms with poor exhaust fans
- Basements with high humidity
- Around windows with condensation
- On wet drywall or wood studs
- Inside air conditioning drip pans
- On carpets or upholstery after flooding
Health Effects to Watch For
Exposure to cladosporium can cause allergic reactions in sensitive people. Symptoms include sneezing, runny nose, itchy eyes, and skin rashes. People with asthma may experience more frequent attacks, and those with weakened immune systems should be cautious.
If you feel unwell and suspect mold exposure, see a doctor for proper guidance. While cladosporium is not known for producing dangerous mycotoxins, it can still irritate your respiratory system. Removing the mold source is the right way to protect your health.
How to Test for Mold
Testing for mold is not always necessary, but it can help identify the specific type. You can purchase DIY test kits, but they have limitations. A more reliable approach is to have a mold professional assess the situation, especially if you see widespread growth.
Professionals use air sampling or surface swabs to confirm mold presence. However, testing does not replace fixing the moisture problem. Even if you know it's cladosporium, the solution is the same: remove the mold and dry the area. If you need help, a water damage inspection can reveal hidden moisture.
When to Call the Pros
Small patches of cladosporium, less than a few square feet, can often be cleaned with soap and water or a mild bleach solution. But if the mold covers a larger area or comes back after cleaning, it's time to call the pros. They have the equipment to dry out walls and remove contaminated materials safely.
Water-damaged drywall and flooring often need to be cut out and replaced. The pros can handle that work, along with drying the underlying structure. If you have had flooding or a persistent leak, professional help prevents mold from returning. Check your policy to see what your insurance covers.
Policies vary, and your insurer decides what is covered.
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Call Now (360) 685-7801Frequently asked questions
Is cladosporium mold dangerous?
Cladosporium is not typically toxic, but it can cause allergic reactions and asthma flare-ups. People with respiratory conditions or weakened immune systems should avoid exposure. If you feel unwell, see a doctor. Removing the mold and fixing the moisture source is the right response.
Can I remove cladosporium myself?
For small areas, you can scrub with a detergent solution and dry thoroughly. Wear gloves and a mask to avoid inhaling spores. But if the mold covers more than a few square feet or keeps returning, professional removal is safer and more effective.
How do I prevent cladosporium from growing?
Control humidity with dehumidifiers and ventilation. Fix leaks promptly and dry wet areas within 24 to 48 hours. Clean air conditioning drip pans regularly and keep bathrooms well-ventilated. In damp climates like Bellingham, check hidden spots like attics and crawlspaces for moisture.
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